Name/Title
MuscoviteEntry/Object ID
78.63.331Description
Chemical Composition: KAl2(AlSi3O10)(F, OH)2
Crystal System: Monoclinic System
Description: Common Name: Muscovite
Chemistry: KAl2(AlSi3O10)(F, OH)2
Location: South Dakota
Descriptionh: Delmar described this specimen as one, crystals of mica, dar, shines like a mirror. A shale like cluster of near black insides and glass like outsides. some corrosion shown on it.
Known as flower like mica and comes from South Dakota
PHYSICAL CHARACTERISTICS:
Color is white, silver, yellow, green and brown.
Luster is vitreous to pearly.
Transparency crystals are transparent to translucent.
Crystal System is monoclinic; 2/m
Crystal Habits include tabular crystals with a prominant pinacoid termination. Muscovites four prism faces form diamond shaped "books" and if modified by another pinacoid they form pseudo-hexagonal crystal "books". The sides of the crystal often tend to tapper. Also as lamellar rock forming masses and small flakes in detrital matterial. Twinned crystals can form flat five pointed stars.
Cleavage is perfect in one direction producing thin sheets or flakes.
Fracture is not readily observed due to cleavage but is uneven.
Hardness is 2 - 2.5.
Specific Gravity is approximately 2.8 (average)
Streak is white.
Associated Minerals are quartz, feldspars, beryl and tourmalines.
Other Characteristics: cleavage sheets are flexible and elastic, meaning they can be bent and will flex back to original shape.
Notable Occurrences include India, Pakistan, Brazil and many USA locallities.
Best Field Indicators are crystal habit, cleavage, elastic sheets, color and associations
Fracture: uneven
Hardness: 2 Gypsum
Luster: Vitreous
Occurrence: Muscovite is the most common mica, found in granites, pegmatites, gneisses, and schists, and as a contact metamorphic rock or as a secondary mineral resulting from the alteration of topaz, feldspar, kyanite, etc. In pegmatites, it is often found in immense sheets that are commercially valuable. Muscovite is in demand for the manufacture of fireproofing and insulating materials and to some extent as a lubricant
Specific Gravity: 2.8
Streak: white
Variety: Muscovite is the most common member of the mica groupCollection
Delmar Smith Mineral CollectionAcquisition
Accession
78.63Source or Donor
Delmar Smith Crystal CollectionAcquisition Method
DonationDimensions
Height
1 inWidth
1 inLength
1/2 inDimension Notes
Dimension taken at widest pointsLocation
Location
Display Case
FS-11Room
Frieda Smith HallBuilding
Crater Rock MuseumCategory
ExhibitMoved By
Ian C.Date
January 29, 2025Notes
Installation/locationLocation
Display Case
FS-6Room
Frieda Smith HallBuilding
Crater Rock MuseumDate
January 3, 2024Location
Display Case
DS-10Room
Delmar Smith HallBuilding
Crater Rock MuseumCategory
PermanentMoved By
Curtis GardnerDate
May 9, 2023Notes
Added current location while cleaning shelf
